This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Epidemiological studies show that Docosahexaenoic Acid (DHA) supplementation slows the progression of cognitive and functional decline over 18 months in mild to moderate Alzheimer s Disease (AD). DHA, an omega-3 fatty acid has been shown to reduce brain levels of beta-amyloid (A[unreadable]) in mice and rat models of AD, as well as have antioxidant effects on the cerebrospinal fluid. Individuals with AD have significantly decreased brain levels of DHA in frontal grey and hippocampus phospholipids compared to controls (as seen in previous human studies), as well as significantly lower plasma levels of DHA compared to control subjects. Since dietary intake of DHA can increase plasma levels of DHA in human subjects, and since dietary intake and plasma levels correlate with brain levels in animals, treatment of AD with DHA supplementation is plausible, and thus proposed in this study. This study will evaluate the effects of DHA versus placebo in subjects with mild to moderate AD over an 18 month period by administering memory and thinking tests. Blood and urine samples will also be collected in this study to examine the micronutrients related to dietary habits which may reveal DHA effects.